[The transposon content of nonconjugated E. coli plasmids].

The search of nonconjugated plasmids in antibiotic-resistant cells of wild E. coli strains was performed and their transposon maintenance has been studied. The possibility of existence of some different nonconjugated plasmids in one bacterial cells was shown and each plasmid could carry the same transposon. Insertion of one transposon into the conjugated plasmid pAP42 resulted in numerous deletions in the genome of this plasmid.